Blood component collection involves separating blood (whole blood) collected from a donor into blood components by centrifugal separation or membrane separation, collecting a required blood component or components, and returning the other blood components to the donor. In blood component collection utilizing a centrifugal separation system, particularly a centrifugal bowl system, a single blood collection needle is used, and a blood collection step and a blood return step are alternately repeated for the purpose of reducing the invasiveness to the donor. Examples of this type of system are described in U.S. Pat. No. 5,494,592 and U.S. Pat. No. 5,607,579.
In typical blood component collection, a needle-piercing portion of the donor is sterilized with alcohol. However, there is a possibility that bacteria present on the skin or subcutaneously can enter the blood component collecting bag together with the blood component.
Some kind of bacteria which have entered the blood collecting bag increase while the blood collecting bag is kept cold. When the blood is transfused into a patient, the patient may suffer from infectious disease or blood poisoning.
The pH of red blood cell conservation liquid (S.A.GM. liquid, OPTISOL liquid, M.A.P. liquid, and the like) currently used is substantially neutral, unlike the conventional blood conservation liquid (anticoagulants such as ACD-A liquid and CPD liquid). Thus, in the red blood cell conservation liquid, bacteria can increase to a high extent while the blood collecting bag is refrigerated.
Because the bacteria are present not only on the skin but also under the skin, careful sterilization of the needle-piercing portion only is not sufficient to prevent them from penetrating into blood.
It is experimentally known that bacteria penetrates into an initial flow of collected blood, together with fragments of skin.
However, a blood collecting device capable of removing the initial flow of collected blood has not been developed.